Electrical current wave changing device



P. D. FLEHR June 1933- ELECTRICAL CURRENT WAVE cumema DEVICE Filed ov. 12. 1925 2 Sheets-Sheet FIE- .L-

Reiuued June 6, 1933 Re. 18,855 g UNITED STATES PATENT OFFICE PAUL D. ILEHB, 01 SAN MATEO, CALIFORNIA nnncrmou. curaann'r wave CHANGING DEVICE Original in. mature, dated This device relates generally to devices for changing the wave form of an electrical cur rent and more specifically to a device'for converting the frequency of an alternating current. In the past frequency converters have involved mechanically moving parts or a multiplicity of operators which were 1 mpractical from a commercial standpoint. It is an object of this invention to devise a frequency converter which will have no mechanically moving parts, will be simple in construction and have a high electrica eflicienc-y; 1

It is a separate core legs which have different magnet c characteristics.

It is a further object of this invention to devise an efiicient form of A and B battery eliminator which may be used as a source of direct current supply for a vacuum tube system such as employed in radio receiving sets. It is proposedito employ a source ofsixty cycle alternating current, convert the 0 frequency of the current to some multiple of sixty, and then rectify and filter the higher frequency. By this method the problem of filtering the rectified alternating current is materially simplified.

Further objects of the invention will appear in the following description in which I have set forth the preferred embodiment of the invention. I

Referring tothe drawings Figure 1 shows a vacuum tube current further object of this invention to 15 devise novel means for producin a resultant October 15, 1988.8er1a1 No. 66,508, fled November 19, 1885. Application for relnue flled-Iune I8, 1981. maria! No. 545,881.

supply system such as contemplated by this invention;

Fig. 2'is a characteristic permeability curve of the material with which one of the core legs is constructed; a 55 Fig. 3 is a characteristic curve of the material with which one of the other core legs is constructed;

Fig. 4 is a curve showing the characteristics of the se arate magnetic fields pro- 59 du igd by the differentially wound primary co1 Fig.5 is a curve showing the usual wave form of sixty cyclealternating current;

Fig. 6 is a curve showin the characteristics of the total magnetic eld produced by the difi'erential action of the primary coils for one-half cycle of the exciting current; a Fig. 7 is a curve showing the waveform of the current in one of the secondary windings of the frequenc converter; and

ig. 8 is a modifie form offrequency 0011- verter.

Referring to Fig. 1, the current wave changing feature of the i vontion comprises generaly an input circuit including prlmary coils 10 and 11 and one or more output circuits including secondary coils 12 and 13. These primary and secondary coils are magnetically coupled together somewhat in the same manner as the usual current transformer.

hen the device is used to convert a'given f; equency into a higher frequenc the primary coils 10 and 11 are connecte to a common source of alternating current, preferably in parallel, for example to a source of sixty cycle alternating current. I

The means for magnetically coupling together the primary coils with the secondary coils include a lurality of metal core legs 14 and 1h upon which the primary coils 10 and 1 are respectively wound. The corresponding ends of these core legs'14 and 15 are positioned together in juxtaposition. and the coils 10 and 11 are so wound that the total effective magnetic field between the points 16 and 17 is produced by the differential eflect of the two core legs 14 and'15. Two side legs 18 and 19 are also provided for the urpose of magnetically coupling together t 0 ends 1e and 17 with the aged ii on which the Secondary coils are wound. T ierefore, the mag netic field which ends to induce a current in the secondary coils 12 and 13 is the resultant magnetic field produced by the differential effeet of the several magnetic fieldsprmlucrd by the-coils 10 and 11.

I The magnetic core-wlegs 14 and are so teristic p'ermeabilit curve than the material magnetic field produced by the core 15. will be noted tiat' at. the point I both of with which the ot er core or cores is con-- structed. For example, one of the cores, say the core 14 is constructed of amaterial which has a permeability curv approximately the curve shown in Fig. 2. tical axis represents permeability while the horizontal axis represents exciting current. It will be seen from this curve that the particular material selected has a high permeability for relatively small exciting current and also has a flat top characteristic,

that is, as the current increases beyond a certain limit, the characteristic curve flattens out or reaches a definite saturation point. material which I prefer to employ is an alloy of nickel and steel. The characteristics of such a material varies with the percentage of nickel, but the high permeability characteristic for relatively small exciting current is most predominate for an alloy which is known as-permalloy which is approximately seventy-oi ht and one-half percent nickel alloyed witi about twenty-two and one-half percent iron.

The material with which thecore 15 is constructed preferably has a characteristic curve somewhat as shown in Fig. 3. The material of which this curve is a characteristic is the-ordinary transformer iron known as high silicon iron. It will be noticed that the 'charactertistic curve of this material does not reach a definite saturation point until relatively strong exciting currents are emKloyed.

s previously mentioned the Cross sectional areas and the current in the coils l0 and 11 are so selected that the characteristics of the magnetic .field produced by the coils 10 and 11 are approximately as shown in Fig. 4. In this'figure the curve 22 represents the characteristic of the total magnetic field produced by the core" 14 while the curve 23 represents the characteristic of the totaIil t the curves areapproximatcly 0, while at the point 2, the curve 22 predominates.

n this curve the ver- The mus

On the other hand at the point 3 the The coils 10 and 11 are so connected together so that the juxta )osed terminals of the cores l4 and 15 are adapted to act differentially upon. each other. That is, at the end 16, the opposedend of the cores l4 and 15 will be north and south respectively for a given impulse of current in the input circuit. Now, neglecting the'pow'er factor, as the current in the input circuit varies from a zero toa maximum from zero to ninety degrees offthe sine wave form, the total resultant magnetic field produced by the two corelegs 14 and 15 acting differentially upon each other will vary substantially in accm-dance to the difference between the two characteristic curves 22 and 23. The horizontal distance to the point 4 represents the maximum magnetization current, which flows in each of the coils. Thus it will be seen as the. current rises from a zero value to a maximum value that it passes through a period eorrespomling to the point 3 where the resultant magnetic field will be zero. On the other hand as the current varies between the points I and ,3, the resultant field passes througlra maximum value of one polarity and as the current varies between the points 3 and 4 it rises to a maximum value of an opposite polarity. exciting current passes through one-half a cycle, that is, from a zero value to a maximum and back again to a zero value at one hundred and eighty degrees, the magnitm'le and polarity of one' of the pole terminals 16 or 17 will vary in accordance with the curve shown in Fig. 6. In this figure, the portion of the curve above the horizontal axis corresponds to a magnetic field of one polarity, while the portions below this section correspond to a magnetic field of opposite polarity. Upon this curve it will be seen that the field at one of the pole terminals will rise to a maximum at three different points as the exciting current passes through one-halfacycle.

Since each of the secondary coils l2 and 13 are magnetically coupled to the transformer .legs 18 and 19 with the terminals 16 and 17,

it will be seen that current will be induced in these secondary coils in accordance with the differential resultant magnetic field produced by the two primary coils. Thus the current induced in one of the secondary coils will vary in accordance with the curve shown in Fig. 7. From this curve it will Thus, as thevaries accordin and if the excitin current to a sixty cycle a ternating current, then t e current in the secondary will be a current of one hundred and eighty cycles which will approximate a sine wave.

In Fig. 1, the frequency converter has been shown as incorporated into a vacuum tube system for supplying the vacuum tube with A and B battery current. For purposesof illustration three vacuum tubes have been shown in the system, numbered. 30, 31 and 32. The first tube, 30, has its nput circuit 33 suitably coupled to a source of modulated carrier frequency energy while the output circuit 34 is suitably coupled to the input circuit 35 of the tube 31. The output circuit 36 of tube 31 is suitably coupled to the input circuit 37 of the tube 32, while the output 011- plet e cycles,

,cuit 38 of the tube 32 is suitably connected 20 to a translator or loud speaker 39. The tube 30 has been shown as a radio frequency amplifier, the tube 31 as a detector, and the tube 32 as an audio frequency amplifier. The respective filaments of the tubes are all ,connected together electrically to the common conductors 40 and 41 while the p0S ll)1V 6 connections for the respective output circuits 34, 36 and 38 are connected together to a common conductor 42.

In order to make-the wave form of the current in the respective output coils 12 and 13 more nearly correspond to a true sine wave,

the two coils 43 and 44 are inserted. As previously mentioned, the converted frequency current in the secondary coil 12 1S employed to supply the B battery current for the vacuum ,tube system. Accordmgly means have been provided for rectifying the output current and for filtering the rectified direct current. For this purpose a unidirectional current device or a rectifier 45 is inserted in the circuit and also a filter of the common T type comprising choke or induetancecofls 46 and 47 and the parallel condenser 48, 1s arrangedto filter out the ripples in the rectified current. Since these ripples will have arelatively high frequency the problem of filtering and minimizing the rlpples w1ll be comparatively simple and the chokes 46 and 47 and the condenser 48 may be relatively small compared to ordinary B battery eliminators. The positive and negative output condensers 49 and 50 are connected respectively to the conductor 42' of theoutput circuit and positive terminal of the Abattery eliminator.

The output circuit for the secondary C011 13 is correspondingly passed through a rectifier 52 and a filtering device comprising chokes 53 and 54 and parallel condenser 55.

The positive and negative output condensers 56 and 57 are connected respectively to the common conductors 41 and 40 of the filaments. One special feature of this arrangement is that the frequency converter not only current will always flow in these coils. This causes the'current flowing in the coils 12 and 13 to be to a certain extent independent of small fluctuations of current in the output circuit.

While the deviceis disclosed as a frequency converter for converting the frequency of the exciting current to some multiple of that fre- (fluency, it is obvious that it may also be used or reducing the frequency of the exciting current. Thus, if the coil 12 is em loyed to excite the coils 10 and 1.1, then the requency which would result from combining the current in the coils 10 and 11 would be one third the frequency of the exciting current in the coil 12. Furthermore, the device is not to be construed as being limited to a frequency converter. The applicant considers the invention to be sufiiciently broad to cover any kind of device coming within the terms of the claims which serve to change the wave form of the exciting current, whether the device is used for merely changing the wave form or for converting the frequency of the exclting current or for rectifying alternating current.

In Fig. 8 a modified form of wave changing device is shown in which magnetic interaction is minimized. In this modification, two closed cores 60 and '61 are provided, the magnetic fields of which have characteristics in accordance with the curves 22 and 23 of Fig. 4. The two primary coils 62 and 63 are connected together to-a common source of alternating current, preferably in parallel. The core legs 64 and 65 are spaced apart by means of a non-magnetic spacer 66 and a secondary coil 67 is wound about both these legs. Current will therefore be induced in the coil 67 in accordance with the differential effect of the fields of the cores 60 and 61.

What I claim is:

1. The method of altering the wave form of -a current comprising causing the current to produce a plurality of magnetic fields having intersecting characteristic filed curves, causing the fields to act differentially upon each other to produce a resultant field, and

utilizing the resultant field to excite a current.

2. In a device of the class described comprising means for causing a current of definite wave form to produce a plurality of m etic fields having difierent characteristidfild curves, said fields being' arranged to act differentially upon each other to produce a a varying resultant field, and means for causin said resultant field to induce a current 0 difi'erent wave form in an output 01rwit.

3. In a frequency converter, an input coil and an output coil, means for magnetically cou ling together said coils, and means for m ifymg said magnetic couplm including a plurality of magnetlcores ma e of materials having difierent permeability characteristics. I

4. In a wave form changing device, .an 1nut circuit including at least two dilferentialy wound primary coils, an output circuit including a secondary coil, and means for ma etically coupling together said coils 1ncludi ng a core for each primary coil of d1fier-' ent permeability characterlstics and arranged-to act difierentially upon each other.

5.. In a wave form chan ing device, an input circuit including at east two p r1ma coils, a core for each primary coil, sald cm and cores bein so selected that the characteristic curve 0 the field of one core is differcut from that of the other core, an output circuit including a secondary coil, and means for coupling together the secondary coil and the rimary coils whereby the resultant field p need by the said cores will induce the output current.

6. In a wave changing device, a transformer having at least two primary windin and a secondary winding, separate magnetic core 1 legs for said primary coils, said core legs being made of dissimilar materialshaving different permeability characteristics.

7. Means for forming a resultant magnetic field comprising a pair of relatively stat onary magnetic cores, and separate windings upon each of said cores adapted to beelectrically excited, said cores being physlcally positioned with respect to each other where: by the component fields of said cores are in opposition, one of said cores being adapted to reach saturation at an exciting current value substantially less than the current value necessary to saturate the other core.

8. Means for forming a resultant magnetic field, comprising at least two relatively stationary electromagnetic elements, means for electrically exciting said elements whereby two component magnetic fields are formed, said elements having difi'erent characteristic magnetization curves and having their component fields acting in opposition to form said resultant field.

9. Means for forming a resultant magnetic field, comprising at least two relatively stationary electromagnetic elements, means for electrically exciting said elements whereb two component magnetic fields are forme said elements having characteristic magneticpeszation curves which intersect in at least two spaced points, and means for combining said component fields to form aresulta'nt field.

10. In a device for'formin a resultant magnetic field vwhich varies lsproportionate y with respect to its exciting current, a pair of relatively stationary magnetic cores made of different materials having difierent permeability characteristics, and windin 5 upon said cores, said cores being physical y arranged to form a resultant field by the combined action of their fields.

11. Means for forming a resultant magnetic field comprising at least two relatively stationary magnetic cores, said cores being made of materials having difierent permeability characteristics, and means for magnetizing eachjof said elements whereby two by their component fie ds act in opposition toaform said resultant field.'

'12. A transformer comprising a pair of cores of magnetic materials having substantiall difierent permeability characteristics, win ings upon each of \said cores, another magnetic core magnetically related to both of said first mentioned cores, and a winding on said last mentioned core.

13. A transformer comprising a pair of cores of magnetic material, one of said cores bein made of a nickel iron alloy capable of relatively high magnetization under small magnetizing currents, another core of ordinary. iron, a winding upon said latter core, another magnetic core magnetically related to both said first named cores, and a winding upon said last named core.

14. The method of forming a resultant magnetic field characterized by the use of two distinct core materials having different permeability characteristic curves adapted to be magnetized by varying current in an exciting circuit, said method comprising combining the component fields of said materials to said materials below saturation for relatively small current values, and magnetizing one of saidmaterials be ond saturation while the other material is be ow saturation for higher current values.

15. A method charactei zed by the use of two distinct core materials having different permeability characteristics and which magnetically intercouple primary and secondary windings, the former of these windings being supplied with varying current from an ex-' citing circuit and the latter of these windings suplying an output circuit; said method comprising combining the component fields of said materials to form a resultant flux magnetizin both of said materials below saturation or small current values in the exciting circuit, magnetizing one of said material is below saturation for higher current values, and utilizing the combined flux from said materials for inducing current in the secondary winding.

16. In a transformer, primary winding means, a secondary winding means, and magnetic path intereoupling said primary and secondary means, one part of said path being formed of ma etic material having high magnetization or relatively small ma netizing current, andanother part of sai path being formed of magnetic material having substantially lower magnetization for the same magnetizing current.

17. In a transformer, primary winding means, a secondary winding means and a magnetic path intercoupling said primar and secondar means, one part of said pat being forme of a nickel iron alloy having relatively higher magnetization for a given magnetizing current than ordinary iron, and another part of said path being formed of ordinary iron.

18. In a device of the character described, a flux modifying assembly including in combination a multi-part'core, a winding on said core, parts of said core being formed of magpredetermined netic materials having different permeability characteristics, one part thereof having a high initial permeability and low saturation as compared with silicon iron while another part thereof has permeability characteristics similar to that of silicon iron.

19. In an electrical device, winding means adapted to be excited by an alternating current supply, composite magnetic core means serving to form a resultant magnetic field of predetermined characteristics, said, core means including two different magnetic materials having intersecting characteristic per- I meability curves, and means adapted to be excited by said resultant field.

20. In an electrical device, winding means adapted to be excited by alternating current supply lines, composite magnetic core means serving to form a resultant magnetic field of characteristics, said core means including a nickel iron alloy art having relatively high magnetization or small magnetizing forces and another art of ferro-magnetic material having a rdlatively lower magnetization for small ma etizing forces but greater magnetization or relatively large magnetizing forces, and means adapted to be excited by said resultant field.

In testimony whereof. I have signed my name to this specification.

PAUL D. FLEHR. 

